GrandMaster config

RPi5_configs/README.md

@@ -9,17 +9,17 @@ GT-U7 GNSS
   ├─ NMEA over UART ──> gpsd/chrony
   └─ PPS on GPIO18  ──> chrony
                          │
-                         ▼
+                         \/
                   CLOCK_REALTIME (UTC)
                          │
                       phc2sys
                          │
-                         ▼
+                         \/
                     eth0 NIC PHC
                          │
                        ptp4l
                          │
-                         ▼
+                         \/
                   PTP domain 0
 ```
 
@@ -115,7 +115,7 @@ refclock SHM 0 refid NMEA offset 0.0 precision 1e-1 poll 3 noselect
 refclock PPS /dev/pps0 refid PPS lock NMEA poll 3
 ```
 
-If this Pi should continue serving NTP to the lab, keep the required `allow` networks, for example:
+Limit the `allow` networks to somethig like RFC1918 range as follows:
 
 ```text
 allow 192.168.0.0/16
@@ -131,7 +131,7 @@ makestep 1 3
 leapseclist /usr/share/zoneinfo/leap-seconds.list
 ```
 
-Do **not** add `local stratum 1` for the GNSS/PPS setup. A selected local refclock already makes chronyd serve the correct NTP stratum; `local` is a separate fallback/local-reference mode.
+<!-- Do **not** add `local stratum 1` for the GNSS/PPS setup. A selected local refclock already makes chronyd serve the correct NTP stratum; `local` is a separate fallback/local-reference mode. -->
 
 Restart chrony and verify that PPS becomes the selected source:
 

RPi5_configs/config.txt

@@ -0,0 +1,7 @@
+
+sudo bash -c "echo '# GPS UART on GPIO14/GPIO15 for Pi 5' >> /boot/firmware/config.txt"
+sudo bash -c "echo 'dtoverlay=uart0-pi5' >> /boot/firmware/config.txt"
+sudo bash -c "echo 'init_uart_baud=9600' >> /boot/firmware/config.txt"
+sudo bash -c "echo '' >> /boot/firmware/config.txt"
+sudo bash -c "echo '# GPS PPS on physical pin 12 / GPIO18' >> /boot/firmware/config.txt"
+sudo bash -c "echo 'dtoverlay=pps-rp1,pin=18,pull-down,schmitt-trigger' >> /boot/firmware/config.txt"

RPi5_configs/phc2sys-gm.service

@@ -0,0 +1,20 @@
+# /etc/systemd/system/phc2sys-gm.service
+
+[Unit]
+Description=Synchronize eth0 PHC from GNSS-disciplined system clock
+After=ptp4l-gm.service
+Requires=ptp4l-gm.service
+
+[Service]
+Type=simple
+ExecStart=/usr/sbin/phc2sys \
+    -s CLOCK_REALTIME \
+    -c eth0 \
+    -w \
+    --step_threshold=0.5 \
+    -m
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target

RPi5_configs/ptp-gm.conf

@@ -0,0 +1,66 @@
+#/etc/linuxptp/ptp4l-gm.conf
+
+[global]
+# extra logging
+verbose               1
+
+# use hardware timestamping (alternative is software, which isn't nearly as accurate/precise)
+time_stamping         hardware
+
+# This needs to be set to full rather than default normal because RPi5 Hardware Rx timestamping doesn't support richer filters. This is why it is better to tell the NIC to timestamp every Rx packet.
+hwts_filter           full
+
+# you can specify a "domain number", which is analogus to VLAN
+domainNumber            0
+network_transport       UDPv4
+delay_mechanism         E2E
+
+# force this node to act as a master (won't revert to slave).
+serverOnly            1
+
+# priority settings, 128 is default. lower numbers are higher priority in case there are multiple grandmasters
+# BMCA priority
+priority1               128
+priority2               128
+
+# clockClass=6 for GNSS reference
+# other classes = https://documentation.nokia.com/srlinux/24-10/books/network-synchronization/ieee-1588-ptp.html
+clockClass            6
+
+# timeSource is where time comes from - 0x10 is "atomic clock" which is a bit sus for us but not ultimately wrong
+
+# |  Value | Meaning               | Use case                                |
+# | -----: | --------------------- | --------------------------------------- |
+# | `0x10` | `ATOMIC_CLOCK`        | Direct atomic/rubidium/cesium reference |
+# | `0x20` | `GPS`                 | GPS/GNSS-disciplined time source        |
+# | `0x30` | `TERRESTRIAL_RADIO`   | Radio time source                       |
+# | `0x40` | `PTP`                 | Synced from another external PTP source |
+# | `0x50` | `NTP`                 | Synced from NTP                         |
+# | `0x60` | `HAND_SET`            | Manually set by human/operator          |
+# | `0x90` | `OTHER`               | Other external source                   |
+# | `0xA0` | `INTERNAL_OSCILLATOR` | Free-running/local oscillator/default   |
+timeSource            0x20
+
+
+
+# Start conservatively. 0x23 would claim <= 1 us.
+clockAccuracy           0xFE
+
+# Unknown/not characterized yet.
+offsetScaledLogVariance 0xFFFF
+
+# PTP/TAI - UTC.
+utc_offset              37
+
+# Two-step is the linuxptp default and is also a good match for Nexus.
+twoStepFlag             1
+
+summary_interval        1
+
+[eth0]
+
+
+# log output to a file, summary interval is 2^x, so 1 = 2^1 = every 2 seconds
+# can also output with -m
+# summary_interval     1
+# logfile             /var/log/ptp4l.log

RPi5_configs/ptp4l-gm.service

@@ -0,0 +1,16 @@
+# /etc/systemd/system/ptp4l-gm.service
+
+[Unit]
+Description=PTP Grandmaster on eth0
+After=network-online.target chrony.service
+Wants=network-online.target
+Requires=chrony.service
+
+[Service]
+Type=simple
+ExecStart=/usr/sbin/ptp4l -i eth0 -f /etc/linuxptp/ptp4l-gm.conf -m
+Restart=always
+RestartSec=3
+
+[Install]
+WantedBy=multi-user.target

RPi5_configs/ptp_nic_coalesce.service

@@ -0,0 +1,13 @@
+# /etc/systemd/system/ptp_nic_coalesce.service
+
+[Unit]
+Description=NIC coalesce minimize
+Requires=network.target
+After=network.target
+
+[Service]
+ExecStart=/usr/sbin/ethtool -C eth0 tx-usecs 4 rx-usecs 4
+Type=oneshot
+
+[Install]
+WantedBy=multi-user.target